The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator. The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport. The ATSB is Australia's prime agency for the independent investigation of civil aviation, rail and maritime accidents, incidents and safety deficiencies.

At
approximately 1650 on 10 February 2010, empty passenger train WP46
was authorised to travel through Manildra Yard on the main line.
However, at the same time a freight train was already standing on
the main line, having recently completed shunting within the yard
limits relating to preparation of train 8938.

The driver of
WP46 heard radio chatter relating to the freight train, so he
broadcast that train WP46 was approaching and was authorised to
travel through Manildra on the main line. The crew of the freight
train immediately replied that they were standing on the main line
and advised train WP46 to stop. Train WP46 had already passed the
yard limit board but the driver had sighted and reacted to a main
line indicator (MLI) showing a red (stop) indication. Train WP46
stopped before passing the MLI, which was located more than 530 m
before the track occupied by the freight train.

While a
number of defences served to avoid a collision in this case, the
event posed a serious safeworking irregularity where one train had
been authorised to proceed over track occupied by a second
train.

The
investigation concluded that the ARTC network controller fulfilled
a shunt order without entering information into the computer system
identifying that both the main line and loop were occupied. The
controller had later forgotten about the track occupancies when
authorising train WP46 to travel through the Manildra Yard.

The ARTC, Pacific National and the Manildra Group have put
processes in place to ensure shunt orders are not fulfilled unless
all shunt operations have ceased and either the main line is clear
or a form of train protection has been implemented in accordance
with the network rules.